Zigzag sewing machine

ABSTRACT

Zigzag sewing machine having a setting member controlled by a rotatably driven control disk, the position of which determines the magnitude and direction of the feeding movements of the feed dog, and a setting arrangement having a setting shaft connected in the transmission train between the scanning member of the control disk and the setting member, for changing the transmission ratio of the control impulses emitted by the control disk, in which the setting shaft of the resetting device is journaled in a lever arm that is pivotally mounted in the machine housing, and extends essentially parallel to a link disposed in the transmission train and engages the pivot point between the transmission train and the setting device, and where the axis of the setting shaft extends through one end point of the rocking range of this pivot point produced by the control disk.

Feb. 1, 1972 United States Patent Vollmar et al.

3,426,712 2/1969 Hanyv et 211......

[54] ZIGZAG SEWING MACHINE Inventors: Kurt Vollmar, Lambsborn; Herbert Wenz,

Kaiserslautem, both of Germany Primary Examiner-Patrick D. Lawson Attorney-Robert H. Jacob G. M. Pfafi AG., Kaiserslautern, Germany 0 7 9 1 4 l L m 211 Appl.No.: 71,996

mines the magnitude and direction of the feeding movements of the feed dog, and a setting arrangement having a setting [30] Foreign Apphcauon Pnomy Data shaft connected in the transmission train between the Sept. 16,1969 Germany...,...............,.

.P 19 46 700.6 scanning member of the control disk and the setting member.

for changing the transmission ratio of the control impulses {52] us. emitted y e control disk, in h ch the setting slum of the [51] lm,Cl, p0s]; 27/00 resetting device is joumaled in a lever arm that is pivolully mounted in the machine housing, and extends essentially parallel to a link disposed in the transmission train and en- Field oi'Search gages the pivot point between the transmission train and the setting device, and where the axis of the setting shaft extends through one end point of the rocking range of this pivot point produced by the control disk.

References Cited 3,015,290 Hale 3Claims,6Drawing Figures BACKGROUND OF THE INVENTION The invention relates to sewing machines, and more in particular to a zigzag sewing machine having a setting member controlled by a rotatably driven control disk, the position of which determines the magnitude and the direction of the feed movement of the feed dog, and with an adjusting or setting device connected in the transmission train between the member scanning the control disks and the setting member, which changes the transmission ratio of the control impulses emanating from the control disk.

In known machines of this type there exists no possibility of changing the control, other than changing the transmission ratio of the control determined by the curvature of the control disk.

Merely one sewing machine with feed control is known, where the control impulses departing from the control disk control a sliding block connected with the feed dog and displaceably journaled in an oscillating rocking slide. By these means the magnitude and the direction of the feed are determined. In this arrangement the control disk is scanned by an angular lever which has a pivot point that is adjustable by means of a setting lever in order to adjust the basic setting of the sliding block. In this manner it is possible to compensate for the deviations between the actual position and the prescribed position of the starting member of the control arrangement that arise for a predetermined point of the curve or cam as a result of tolerance errors of the control disk and due to play occurring in the transmission gear.

SUMMARY OF THE INVENTION As compared to this, it is an object of the invention to provide possibilities for the extensive modification of a basic pattern that depends on the curvature of the control disk in order to increase the range of usefulness of the machine without exchanging the cam disk.

Thus, it is an object of the invention to effect the arrangement of the setting means for the stitch length in the transmission train between the cam disk and the setting member in a manner that the location of the control range that can be transferred by the control disk is variable within the range of feeding which extends from the maximum forward or rearward direction of sewing.

In accordance with the invention, this problem is solved in that the setting shaft of the setting device is journaled in a lever arm pivotally mounted in the housing of the machine, which extends essentially parallel to a link that is disposed in the transmission train and engages at the joint between the transmission train and the setting device, and that the axis of the setting shaft extends through the one terminal point of this pivotjoint of the rocking range produced by the control disk. In this manner, it is possible by setting the lever arm to the different rocking positions to produce with one and the same cam disk a plurality of stitch formations that differ in form essentially from one another.

In a preferred embodiment of the invention, an abutment disposed on the machine housing extends into the path of movement of an abutment cam rigidly connected with the setting shaft, which rocks the lever arm into such a position that the setting member that is in operative connection with the setting shaft assumes a predetermined angular position for the maximum given impulse deflection of the scanning member of the control disk. In this manner it is accomplished that the magnitude of the rocking movement of the feed dog does not exceed a predetermined amount that depends on the conditions given by the machine.

It is particularly suitable to utilize the abutment for limiting the rocking range of the fed dog as the setting means for the basic adjustment of the setting member that guides the feed dog by locating it on the housing for adjustment radially with respect to the setting shaft BRIEF DESCRIPTION OF THE DRAWINGS Further features of the invention and details about the advantages obtained thereby will become apparent from the following description of an embodiment illustrated in the accompanying drawings in which FIG. 1 shows a front view ofa sewing machine.

FIG. 2 is a perspective illustration of the drive mechanism for the feed dog of the sewing machine,

FIG. 3 is a section along the line lII--Ill in FIG. 1,

FIG. 4 is a front view of a detail of the transmission gear illustrated in FIG. I in somewhat modified form, and

FIGS. 5 and 6 show two different stitch formations produced with the sewing machine in accordance with the invention. 1

DESCRIPTION OF THE INVENTION The sewing machine illustrated in FIG. 1 comprises a housing in which an arm shaft 2 isjournaled which drives a needle bar 4 with a needle 5 by way of transmitting mechanism 3 disposed in the housing 1 and a shaft 7 by way of a toothed belt 6 (FIG. 2) journaled in the housing 1, as well as a lower shaft 9 by way ofa further toothed belt 8. The looper which is not illustrated is connected with the shaft 9 by way of a gear transmission, likewise not illustrated.

The needle bar 4 isjournaled in a needle bar frame 10 (FIG. 1) which is connected by way of a pusher bar 11 with a rocker 12 for producing rocking movements in a direction which is lateral with respect to the direction of feed. The rocker has a sliding block 14 which is guided in an adjusting slide 13journaled rotatably in housing 1. The angular position of the adjusting slide 13 may be changed by means ofa setting knob 15 connected with it, that projects from the housing I.

A link member 16 is connected with the rocker 12 (FIG. 3) and is linked in turn to a push member 17. The push member 17 has forked prongs 18 at its lower portion which are guided in grooves 19 of a straight guide 20 mounted on the shaft 7. The push member 17 has a stud 21 which cooperates with a guide groove 22 (FIG. 1) on a guide disk 23 mounted on the shaft 7.

A second control disk 24 (FIG. 2) is secured to the shaft 7 and has guide groove 25 which is engaged by a stud 27 carried by a scanning member 26. The scanning member 26 is secured on a rocking shaft 28 journaled in the housing 1 of the machine and carries a lever arm 29 which is connected with a bolt 31 by way of a link 30. Bolt 31 is engaged by a link 32 which is connected by way of a link bolt 33 with an angular lever journaled upon a shaft 34 in the housing 1.

The angular lever 35 is connected by way ofa link 36 with a lever arm 37 which is secured in the lower part of the housing 1 upon one end ofa setting member 38'which is in the form of a shaft. The other end of the setting member 38 carries a lever arm 39 which is rotatably connected by way of pin 40 with a link member 41 of equal length. The link 41 is loosely journaled on a bolt 42 that is fastened to an eccentric bar 43 and carries a further link member 44 which corresponds in length to link 41. The eccentric bar 43 encompasses at one end an eccentric 45 that is secured to the shaft 9.

The link member 44 is in communication by way of a stud 46 with the crank arm 47 of a shaft 48 journaled in the lower part of the housing 1. A bifurcated lever 49 is secured upon that shaft to which a support 51 equipped with a feed dog 50 is pivotally connected. The support 51 is connected by way of an eccentric bar 52 with an eccentric 53 mounted on shaft 9 which imparts vertical lift movements to the feed dog 50.

A link member 54 of the same length as link member 32 is in engagement with the bolt 31 that is connected with link member 30. The link member 54 is connected by way of a link bolt 55 with a crank arm 56 of equal length as link member 32. A setting shaft 57 is mounted on crank arm 56 which together with the crank arm 56, the link bolt 55, link member 54 and bolt 31 constitutes the adjusting mechanism 58 which is journaled in a lever arm 59 by way of setting shaft 57. The lever arm 59 is rockably supported by a pivot bolt 60 mounted in the housing 1 and has a further arm 61 that extends from the housing 1 of the sewing machine and carries a scale 62.

A lever arm 63 is secured to the setting shaft 57 that is in communication with a double lever 65 journaled on the pivot bolt 60 by way of link 64 whose free end extends from the housing 1 of the machine to the scale 62.

The scale 62 is provided with a slot 66 against which rests one abutment surface 67 of the double lever 65. in the double lever 65 a screw 68 is threadedly received which extends through the slot 66. Upon loosening the screw 68, the angular position of the double lever 65 may be changed with respect to the arm 61 of the lever arm 59 and secured in the adjusted position by turning the screw 68 whereby the scale 62 is clamped between the abutment surface 67 and the head of the screw 68.

The lever arm 59 is connected by way of a link member 69 with a double lever 70 which rests loosely upon the pivot pin 34 and has its free end likewise extend from housing 1 where it forms a grip 71.

The double lever 70 has a recess 72, as well as a rack of teeth 73. The adjusting slide 74 which encompasses the double lever 70 in the area of the recess 72 has a latch pin which cooperates with the teeth of the rack 72 and is provided with an aperture 75 that is bounded by an abutment surface 76 that extends obliquely to the side walls and an abutment surface 77 which extends parallel to these edges for an abutment pin 78 that is fastened in the housing 1 and extends through the aperture 75, as well as through recess 72.

A draw spring 79 hooked onto lever arm 59 whose other end is secured to the housing 1 of the machine pulls the mechanism described in a position of adjustment determined by the engagement of the abutment surface 76 with the abutment pin 78.

The lever arm 63 is provided with an enlargement 80 which is limited by an abutment cam 81. By rotating the lever arm 63 about the setting shaft 57 and also by rocking the lever arm 59 about the axis bolt 60, the abutment 81 can be brought into engagement with an abutment 82 which may also be adjustably secured in the housing 1. As a result, any angular displacement of the setting member 38 which is too large, and thus too large a displacement movement of the feed dog 50 is avoided. The abutment cam 81 is of such shape that the setting member 38 does not exceed the angular position in one direction of turning which the feed dog 50 assumes upon reaching the maximum step length that can be executed. In the other direction of turning of the setting member 38 the maximum terminal position is determined by the abutment surface 77 of the aperture 75 of the setting slide 74.

ln the modified embodiment shown in PK]. 4, the abutment 82 is replaced by a setting screw 83 which has a circular incision 84 which is adjustable by rotating the setting screw 83 with respect to a scale 85 secured to the housing. In this embodiment the parts 74 and 75 are eliminated. A safety abutment 86 secured to housing 1 limits the range of rocking of the lever arm 59 upon the side which is opposite the setting screw 83.

The arrangement operates as follows:

The arm shaft 2 drives the shaft 7 at a reduced number of rotations determined by the selected transmission ratio. The two control disks 23 and 24 rotate with the shaft 7. By these means the link is displaced radially with respect to shaft 7 in accordance with the profile of the control groove 22 of the control disk 23 by way of the stud 21 and the sliding member 17. In this connection it displaces the sliding block 14 in the setting slide 13 by way of the rocker 12. Depending on the position of the setting slide 13 that is variable by means of the setting grip 15, the rocker 12 carries out in addition to its rocking movement a sliding movement of less or more magnitude in the axial direction of the sliding bar 11. This sliding movement guides the sliding bar 11 upon the needle bar frame so that the needle bar 4 journaled therein effects stitch movements that are directed perpendicularly to the direction of the feed ofthe machine.

The control disk 24 transmits from its control groove 25 by way of stud 27 and the scanning member 26 rocking impulses which correspond to the outline of the control groove 25. These impulses are transferred by way of lever arm 29, links 30 and 32, angular lever 35 and link 36 to the crank arm 37 and thereby to the setting member 38.

The setting member 38 by its rotating movements carries along the lever arm 39 and thus displaces the stud 40 which serves as axis of rotation for the link 41 with respect to the stud 46. During the rocking movement of the bolt 42 imparted by eccentric bar 43 the link 41 therefore effects a true rotary movement about the stud 40, while the link 44 besides this rotary movement also effects a movement relative to the shaft 48.

This relative movement is transferred by the crank arm 47 as a rocking movement onto lever 49, which imparts a lifting movement in feeding direction to the feed dog 50 by way of support bar 53. The magnitude and direction of this feeding movement depends on the position at the time of the setting member 38 and, therefore, on the magnitude of the difference in setting between the studs 40 and 46.

The feed dog 50 receives its lifting movement in vertical direction from the eccentric 53 by way of eccentric bar 52 The device described above serves for controlling the feeding movement and direction as determined by the impulses that emanate from the control groove 25 of the control disk 22. The magnitude of transmission of these impulses can be changed by the control device 58. For this the knurled screw 68 is released, its position is changed within the slot 66 of the scale 62, and the selected mutual position is set by fastening the knurled screw 68. During rotation of the double lever 65 with respect to the scale 62 the link 64 turns the crank arm 56 by way of lever arm 63 and the setting shaft 57. The crank arm displaces the link bolt 55 which serves the axis of rotation for the link 54 with respect to the link bolt 33.

During the swinging movement of the bolt 33 caused by link 30 the link 54 effects a true rotary movement about the link bolt 55, while the link 32 effects also a relative movement about the axis 34 in addition to this rotary movement. This relative movement is transmitted by the angular lever 35 as a setting component onto the setting member 38.

The transmission ratio between the deflection of link 30 and the deflection of the link 36 connected therewith therefore depends on the existing position of the setting shaft 57 and thus on the magnitude of the difference in displacement between the link bolts 33 and 55. Thus also the setting impulses that emanate from the control cam 25 can be changed in their magnitude between G and a maximum value in accordance with the setting of the knurled screw 68 on the scale 62.

The grip 71 provided on the double lever 70 is held in raised position by the spring 79. In this connection the abutment surface 76 is in engagement with the abutment stud 78. By displacing the setting slide 74 a different basic setting of the setting member 38 can be obtained, because due to the obliquely extending abutment surface 76 the angular position of the double lever 70, and thus also the angular position of the lever arm 59 connected with the link 69, changes. At the same time the setting shaft 57 journaled in the lever arm 59 is turned, whereby the crank arm 56 turns the setting member 38 to the changed basic setting by way of links 54 and 32, the angular lever 35, the link 36 and the crank arm 37.

The expression basic setting designates the angular position of the setting member 38 set by way of setting slide 74 as the transmission ratio 0 is set on the scale 62. In this connection no setting impulses are imparted by the control groove 25, so that the setting member 38 retains the same basic setting for all impulse emissions of the control groove 25. Thus a constant feed is effected in forward or reverse direction, the magnitude and direction of which depends on the value to which the setting slide '74 is set.

Inasmuch as the angular position of the setting member 38 determines the amount of feed of the dog, the basic setting of the stitch length can be indicated in mm. on the scale of the double lever 70. The setting slide 74 can be displaced in the present embodiment between basic settings of the setting member 38 which correspond to a magnitude of feed of the feed dog 50 of about 4.5 mm. forward feed to about 2 mm. feed in reverse direction. 1

Upon setting of the desired basic setting the transmission ratio of the setting impulses is set by corresponding setting of the double lever 65 relative to the scale 62. The setting impulses emanating from the control disk 24, determined by the form of the control groove 25, are then superimposed on the basic setting of the setting member 38 at the ratio of magnitude that depends on the setting of the double lever 65.

By changing the transmission ratio between the guide groove 25 and the setting member 38 by adjusting the terminal surface 67 of the double lever 65 to a number between 0 and 6" on the scale, the setting member 38 swings in accordance with the setting impulses determined by the control groove 25 within a range of rotation limited by the maximum deviations of the control groove 25. This range of rotation of the setting member 38 is adjustable in magnitude by changing the transmission ratio of the control impulses and in regard to its position by changing the basic adjustment.

The control groove is so shaped in the present embodiment and connected by means ofa suitable linkage with the bolt 31, that its maximum deflection directed against the axis of the control disk 24 effects a coaxial alignment of the bolt and the setting shaft 57, while the deviations of the control groove 25 directed toward the border of the control disk 24 effect a setting difference of said maximum swing or deflection between the bolt 31 and the setting shaft 57. This measure has the advantage that the setting member 38 assumes the set basic position at the adjusting slide 74 during the maximum setting impulse of the control groove 25 directed towards the axis of the control disk 24, and that the range of rotation of the setting member 38 set by the choice of the transmission ratio of the control impulses of the control groove 25 extends from this basic setting only in one direction. The maximum deflection of the control groove 25 directed against the axis of the control disk 24 thus leaves the setting member 38 in the ad justed basic setting. Thus, this deflection may be designated as setting impulse having the value Of All remaining deviations from the aforementioned setting impulse 0" directed against the border of the control disk 24 turn the setting member 38 in that direction, which produces a reduction of the feed value at the material feed dog 50, as the case may be in the reverse feed direction. The maximum deviation of the control groove 25 toward the border of the control disk 24 can be designated as setting impulse having the value l The scale 62 may be scored in such a manner that the setting impulse of the control groove 25 having the value l turns the setting member 38 through such an angle out of the said basic setting that there results a change in stitch length in mm. with the value to which the scale 62 is set with respect to the set basic setting.

In view of the possibility of displacing the basic setting of the setting member 38 in the positive as well as also in the negative direction of feed it is possible with a single cam disk to obtain manifold effects for the forward feed control. For example, with a control disk or cam 23 for the zigzag guidance to produce a zigzag series of stitches where each over stitch consists of three stitches and a control disk 24 for the material feed that produces a series of impulses of the values l-0-l, the basic setting of the setting member 38 at the setting slide 74 can be set to forward feed l-4" (basic setting), and simultaneously the terminal surface 67 of the double lever 65 can be st to the transmission ratio of 4 of the scale 62. Then a setting impulse of the value 0" effects a forward movement on the feed dog 50 of 4 mm. in the forward direction and a setting impulse of the value l an advancement decreased by 4 mm., i.e., standstill, so that with rhythmic sequence of the setting impulses l-O-l in cooperation with the zigzag control obtains, for example, the stitch formation illustrated in FIG. 5.

With the same control disks 23 and 24 the setting impulse having the value 0 effects with a basic setting of the setting slide 74 at :H (new amount of basic setting) a forward feed of the feed dog of 3 mm. in forward direction, while the setting impulse having the value 1" while the transmission ratio of 4" is maintained results in a forward movement decreased by 4 mm., i.e., a forward movement of the feed dog 50 by 1 mm. in the reverse direction, because the setting impulse having the value I turns the setting member 38 by four units of forward movement against the negative direction of feed. In that case the stitch formation illustrated in FIG. 6 is produced. With other basic settings by means of the setting slide 74 and by changing the transmission ratio of the transmitted impulses on the scale 62, a large number of further deviating stitch formations can be produced.

The abutment cam 81 at the lever arm 63 serves to ascertain that the feed dog 50 will not effect a larger feed movement than what it may effect on the basic of structural requisites. As soon as by means of the setting of the double lever 65 and/or the setting of the setting slide 74 such an angular turning of the setting member 38 would be set, that the control groove 25 would impart to the feed dog 50 a stroke exceeding its maximum permissible feed stroke, the abutment cam 81 abuts against the abutment 82 as the double lever 65 and/or the setting slide 74 are reset, and limits the adjustable basic setting of the control disk 38, dependent on the position of the double lever 65. The setting impulses transmitted to the control disk 38 by the control groove 25 thus impart to the feed dog feed strokes which are below its maximum possible feed stroke.

In the modification illustrated in FIG. 4 the basic setting of the setting member 38 is effected by means of the setting screw 83, the groove 84 of which is set to the desired value of the scale 85. With further setting of the double lever 65 at the scale 62 it is then possible to select the desired transmission ratio for the setting impulses emitted by the control groove 25.

Since the abutment cam 81 connected with the lever arm 63 rests against the setting screw 83 under the effect of spring 79, an adjustment of the double lever 65 with respect to the scale 62 by way of link 64 effects a rotation of the lever arm 63 about the setting shaft 57. The abutment cam 81 in this connection effects a turning of the setting shaft 57 about the bolt and turns the setting shaft 38 by way of the gear members 56, 54, 32, 35, 36 and 37 into a new basic setting, which differs with respect to the basic setting for the transmission ratio 0 by the amount set on the scale 62 in the negative feed direction. Also here the setting impulses emitted by the control groove 25 are forwarded as negative amounts to the setting member 38, so that this member when the machinc is driven describes a rocking range between the newly set basic setting and a value reduced by an amount set at the scale 62. If, for example, a feed movement of 4 mm. in forward direction is set on the setting screw 83, there results for a set amount of two units on the scale 62 a basic setting of 42=2 mm. stitch length in the forward direction. The feed dog thus effects forward feed strokes which, depending on the magnitude of the setting impulses, produce stitch lengths in the forward direction between 0 and 2 mm.

The safety abutment 86 limits the possibility of turning the lever arm 59 which can be adjusted for the setting of screw 83 as well as also for the setting of the double lever and thus also the turning of the setting member 38 into such a terminal position where the feed dog 50 effects its largest rearward stroke.

Having now described our invention with reference to the embodiment illustrated in the drawings, what we desire to protect by Letters Patent is set forth in the appended claims:

1. In a zigzag sewing machine of the type having a rotating control disk supported on a driven shaft in the housing of the machine, a setting member operatively linked to said control disk, a feed dog operatively connected to said setting member to determine the magnitude and the direction of the feed movements, scanning means operatively connected to said control disk, a gear train operatively linking said scanning means to said setting member, an adjusting means inciuding a setting shaft forming a part of said gear train operative to change the transmission ratio of the control impulses emitted by said control disk, said adjusting means including manual operating means, a pivot joint between said adjusting means and said gear train, a lever arm pivotally mounted in the housing of the machine and supporting said setting shaft, a link member extending generally parallel to said lever arm and connected to said pivot joint between said gear train and said adjusting means, said setting shaft having an axis extending through one end point of the path of angular movement of said pivot joint generated by said control disk.

2. Sewing machine in accordance with claim I, including an abutment cam connected to said setting shaft, and an abutment member in said housing extending into the path of move ment of said abutment cam operative to place said lever arm into a position where said setting member which is linked to said setting shaft is placed in a predetermined angular position corresponding to the maximum impulse deflection of said scanning means, and a double-armed lever having one arm connected to said pivotally mounted lever arm and provided with an adjusting slide means at its other arm.

3. Sewing machine in accordance with claim 2 where said abutment is adjustably mounted in said housing for movement in a direction radially with respect to said setting shaft. 

1. In a zigzag sewing machine of the type having a rotating control disk supported on a driven shaft in the housing of the machine, a setting member operatively linked to said control disk, a feed dog operatively connected to said setting member to determine the magnitude and the direction of the feed movements, scanning means operatively connected to said control disk, a gear train operatively linking said scanning means to said setting member, an adjusting means including a setting shaft forming a part of said gear train operative to change the transmission ratio of the control impulses emitted by said control disk, said adjusting means including manual operating means, a pivot joint between said adjusting means and said gear train, a lever arm pivotally mounted in the housing of the machine and supporting said setting shaft, a link member extending generally parallel to said lever arm and connected to said pivot joint between said gear train and said adjusting means, said setting shaft having an axis extending through one end point of the path of angular movement of said pivot joint generated by said control disk.
 2. Sewing machine in accordance with claim 1, including an abutment cam connected to said setting shaft, and an abutment member in said housing extending into the path of movement of said abutment cam operative to place said lever arm into a position where said setting member which is linked to said setting shaft is placed in a predetermined angular position corresponding to the maximum impulse deflection of said scanning means, and a double-armed lever having one arm connected to said pivotally mounted lever arm and provided with an adjuSting slide means at its other arm.
 3. Sewing machine in accordance with claim 2 where said abutment is adjustably mounted in said housing for movement in a direction radially with respect to said setting shaft. 